Skin-contacting (non-invasive) electrodes are now widely used in conjunction with medical apparatus both to monitor patient conditions and to deliver an electrical signal through the electrode to the patient, including delivery of such signals for a variety of purposes, including wound treatment, and, particularly, to enhance soft tissue wound healing.
Where the electrode is to be used in a passive manner to sense a patient condition or provide an electrical signal return path, the requirements for such an electrode are not as strenuous as are the requirements for an active electrode used to deliver a voltage or current through the skin to the patient. In like manner, the requirements for a non-invasive electrode to be in contact with intact skin is not as strenuous as are the requirements for such an electrode that is to be utilized in contact with a soft tissue wound, and particularly a soft tissue wound that is open as is most often the case.
Where the electrode is to be in contact with the wound, the electrode needs to be rated for blood contact (which requires a higher degree of biocompatibility than does an electrode that contacts intact skin), and the materials used in the electrode need to tolerate sterilization (including ability of the materials utilized to avoid break-down or thereafter present an undesirable appearance), must not be subject to ion or chemical migration (which can occur, for example, where the electrode is metallic and/or where potentially toxic materials are utilized), must not shed particles (which can occur, for example, where the skin contact layer is of cotton), and must not unduly cause corrosion (which can occur if a liquid, such as saline solution, escaping from the electrode comes into contact with metallic portions of the releasable connector through which current is applied to the electrode).
In addition, an electrode used for wound contact needs to include materials that allow contouring of the electrode to effect good wound contact over the entire area of the electrode, not include materials that prevent uniform transfer of the signal (such as current) to the patient over the entire dispersing area of the electrode, not include materials that prevent or fail to provide proper skin moisture at the wound to be healed, and be sufficiently economical to allow the electrode to be disposable from a practical standpoint.
Thus, realization of a practical and yet effective disposable wound treatment electrode to be in wound contact is not simple, and presents considerably more difficulty than would be encountered in making a passive electrode or in making an active electrode to be in contact with intact skin.
With respect to known prior art, U.S. Pat. No. 4,817,594 (Juhasz) shows a wound dressing with an envelope formed from sheets of permeable and semi-permeable material at one side and a non-adherent, wound contactable sheet of permeable material at the other side, with an electrically non-conductive charcoal fabric (chosen specifically for its anti-bacterial characteristics) engaging an electrically conductive open mesh (which may be nylon impregnated with a metal such as silver) within the envelope. Mention is also made in U.S. Pat. No. 4,817,594 that means may be provided to provide a voltage to the silver impregnated open mesh material and that good conductivity can be ensured by hydrating the dressing prior to use with isotonic saline.
U.S. Pat. No. 4,638,796 (Sims) shows a method of dressing a wound that includes use of a non-adhering barrier material, and U.S. Pat. No. 4,142,521 (Konikoff) shows electrostatic soft tissue wound repair enhancement using electret elements with gauze between the electret elements and the wound site.
U.S. Pat. No. 4,919,148 (Muccio) shows transcutaneous electrical stimulation using an electrode assembly having a carbon-rubber electrode with a boss having a bore therein to receive a connector pin, with the electrode having a non-conductive sheet at one side and a woven fabric at the other side forming an enclosure with the electrode and a gel-receiving cavity therein.
U.S. Pat. No. 4,926,878 (Snedeker) shows a medical electrode suitable for use with a TENS unit with the electrode including a stud fastener engaging a disperser layer and with the electrode having a gel, such as hydrogel, engaging the dispersive layer, while U.S. Pat. No. 4,248,247 (Ware et al.) shows a post-operative electrode with a conductive sheet formed of rubber with carbon therein, and U.S. Pat. No. 4,300,575 (Wilson) shows an air-permeable disposable TENS electrode that includes a carbon filled silicone rubber pad.
U.S. Pat. Nos. 4,934,383 and 4,422,461 (Glumac) show a TENS and/or post-operative (post-op) electrode having a metal layer and a carbon-containing conductive layer, U.S. Pat. No. 4,870,969 (Swartz) shows a medical electrode having a metal foil between a conductive plastic film and a layer of hydrogel and with a stud fastener extending through a backing layer, U.S. Pat. Nos. 4,777,954 and 4,706,680 (Keusch et al.) show an electrode with a hydrogel layer in contact with a metal snap extending through a backing, U.S. Pat. No. 4,640,289 (Craighead) shows a biomedical electrode having a metalized layer contacting a snap extending through a retainer sheet, and U.S. Pat. No. 4,633,879 (Ong) shows an electrode having a metal snap that extends through a backing to a layer of conductive adhesive.
U.S. Pat. No. 4,955,381 (Way et al.) shows a stimulating and monitoring electrode having a metal disperser with wires connected thereto extending from the electrode through a plastic foam cover and with a conductive polymer (hydrogel) layer adjacent to the metal disperser, U.S. Pat. No. 4,771,783 (Roberts) shows a biomedical electrode having an electrically conductive metal film connected through the edge of the electrode to a lead wire, U.S. Pat. No. 4,911,657 (Berlin) shows an EKG electrode having a metal layer and gel matrix with a plug insertable through an insulating sheet to the metal layer, U.S. Pat. No. 4,895,169 (Heath) shows a stimulating electrode having a metal conductive plate, a porous foam disc to receive saline gel, and a holding ring at the opposite side from the foam base, and U.S. Pat. No. 4,893,626 (Henley et al.) shows an electrode having a natural rubber insulating layer next to an adhesive tape backing and an aqueous gel layer that is conductive.
U.S. Pat. No. 4,635,642 (Cartmell et al.) shows a disposable electrode having spaced foam sheets, hydrogel between the sheets, and a plug-in connector insertable through a hole in the top of one sheet, U.S. Pat. No. 4,243,051 (Wittemann) shows a disposable electrode with a mesh disperser that includes a metal and a fabric backing with the disperser connected to a wire lead that is positioned across the disperser, and U.S. Pat. No. 4,237,886 (Sakurada et al.) shows an electrode having a substrate that includes a textile with conductive fibers and a conductive adhesive layer that includes carbon fibers.
U.S. Pat. No. 4,798,208 (Faasse, Jr.) shows a diagnostic electrode with a tab extending from one edge thereof that is engagable by an alligator-type clip, and U.S. Pat. No. 4,657,023 (Kuhn) shows an electrode for use with ECG measuring apparatus having a metallic layer with an upwardly extending tab engagable with an alligator-type clip.
The use of electrical apparatus and methods for enhancing healing of a soft tissue wound is shown in U.S. Pat. No. 4,846,181 (Miller) and apparatus for enhancing healing of a soft tissue wound is shown in U.S. Pat. No. 4,895,154 (Bartelt et al.) both which are owned by the assignee of this invention. U.S. Pat. No. 4,738,250 (Fulkerson et al.), U.S. Pat. No. 4,919,138 (Nordenstroom), U.S. Pat. No. 4,922,906 (Takeuchi et al.) and U.S. Pat. No. 4,895,153 (Takeuchi et al.) also show apparatus for applying electronic signals to a wound area to facilitate healing.
As can be appreciated from the foregoing, while electrodes, associated connectors and/or methods of utilization have heretofore been suggested for various purposes including enhancing wound treatment, improvements can still be utilized to good advantage.